The present invention relates to a surface mounted package for accommodating pulse transformers and common mode choke coils, which constitute a LAN (local area network) for connecting electronic office equipment, and a pulse transformer module for LAN using the same.
Parts for LAN consisting of pulse transformers and common mode choke coils are required to be compact and thin in conjunction with requirements for the miniaturization of electronic office equipment such as personal computers. To cope with such requirements, JP-A-2004-281727 has already proposed a package such as the one shown in FIG. 12. This package is arranged such that pulse transformers (hereafter, sometimes referred to as PTs) 51 and 52 on reception and transmission sides, as well as common mode choke coils (hereafter, sometimes referred to as CMCs) 53 and 54 which are respectively connected to these PTs 51 and 52, are accommodated in a package 55. The package 55 has recessed portions 56 and 57 for respectively accommodating the PTs 51 and 52 and recessed portions 59 and 60 for accommodating the CMCs 53 and 54.
Reference numerals 61 to 66 denote terminals which are fixed to one terminal fixing edge 67 of the package 55, and numerals 68 to 73 denote terminals which are fixed to the other terminal fixing edge 74. The terminals 61 and 62 are terminals for connecting the terminals of the primary winding of the PT 51, and the terminal 63 is a terminal which is connected to a center tap of the primary winding of the PT 51 through a wire. The terminals 65 and 66 are terminals for connecting the terminals of the primary winding of the PT 52, and the terminal 64 is a terminal which is connected to a center tap of the primary winding of the PT 52 through a wire.
Lead wires of the secondary windings of the PTs 51 and 52 are respectively wound around the CMCs 53 and 54. The lead wires of the secondary winding of the PT 51 wound around the CMC 53 are connected to the terminals 68 and 69. The lead wires of the secondary winding of the PT 52 wound around the CMC 54 are connected to the terminals 72 and 73. The terminals 70 and 71 are respectively connected to center taps of the secondary windings of the PTs 51 and 52 through wires.
Toroidal cores of the PTs 51 and 52 mounted in this package 55 have larger diameters than toroidal cores of the CMCs 53 and 54, the PTs 51 and 52 are located on both end sides of the package 55, and the CMCs 53 and 54 are disposed at the clearance between the PTs 51 and 52. In addition, as the CMCs 53 and 54 are disposed in terminal intervals a and b of the terminals 63 and 64 as well as 70 and 71 in central portions of the terminal fixing edges 67 and 74, the width W in opposing directions of the terminal fixing edges 67 and 74 of the package 55 are set to a predetermined width or less, thereby making the package 55 compact.
In the package shown in FIG. 12, the CMCs 53 and 54 are disposed in the clearance between the PTs 51 and 52, and the space where the CMCs 53 and 54 are disposed is secured by making use of the intervals between the terminals 63 and 64 and the terminals 70 and 71, thereby making it possible to set width W in the opposing directions of the terminal fixing edges 67 and 74 to a small width and realize the miniaturization. However, with such a layout, there is a drawback in that the routing of the leads of one CMC becomes long, and an adverse effect has been imparted to the insertion loss characteristic.